slow game graphics in lxc container

I have a privileged lxc container running on Ubuntu 16.0.4 LTS.

I have noticed that the graphics of our game are very sluggish in container compared to when running on host directly.

Could anyone point a reference as to what could be the cause ?

So I ran glxgears application inside the container. Though the application ran fine but I saw the following info + errors on console:

libGL error: failed to open drm device: Permission denied
libGL error: failed to load driver: nouveau
4057 frames in 5.0 seconds = 811.356 FPS
4238 frames in 5.0 seconds = 847.557 FPS
4251 frames in 5.0 seconds = 850.081 FPS
4254 frames in 5.0 seconds = 850.743 FPS
4253 frames in 5.0 seconds = 850.431 FPS
4255 frames in 5.0 seconds = 850.949 FPS
4253 frames in 5.0 seconds = 850.450 FPS
4254 frames in 5.0 seconds = 850.733 FPS
4250 frames in 5.0 seconds = 849.960 FPS
4247 frames in 5.0 seconds = 849.254 FPS
4246 frames in 5.0 seconds = 849.129 FPS

1 Answer

I got it fixed. First, we have to make sure that the user inside lxc container belongs to the group video. To do this, do the following: ( assuming user is named ubuntu )

sudo usermod -a -G video ubuntu

Then, add the following in the container config file i.e. /var/lib/lxc/mk7i_container/config. My container name is mk7i_container.

#Video DRI
lxc.cgroup.devices.allow = c 226:* rwm
##/dev/dri mounts
lxc.mount.entry = /dev/dri dev/dri none bind,optional,create=dir

Now, restart the container. And the graphics should work fine.